A small slope failure from earthquake-related subsidence in the harbor of Hereke

Jose C. Borrero University of Southern California

Copyright Information: All images are in the public domain and available for free. If you use this image, credit NOAA/NGDC, Jose C. Borrero, University of Southern California.

Note the submerged tree in the center of the photo and undermining on the slope. The town of Hereke, on north Izmit Bay, had a small harbor and a municipal pier. The local police office reported that the wave came up a small inlet and flooded to a depth of 50 cm over the parking area in front of the police station. There was a significant slope failure on the east side of the harbor about 60 m long by 12 m wide. A one-meter by 30 cm concrete sidewalk also fell into the harbor along the entire length of the slope failure.

On August 17, 1999, at 3:02 am local time (00:02 GMT) a magnitude (Mw) 7.4 earthquake occurred on the northern Anatolian fault. The epicenter was located very close to the south shore of the Bay of Izmit, an eastward extension of the Marmara Sea. The location of this earthquake and its proximity to a populous region on the Bay of Izmit contributed greatly to its damaging effects. The total estimated loss for port facilities in the region was around $200 million (US). Subsidence and slumping caused much of the coastal damage, but a tsunami was generated that also caused coastal damage and deaths.